In recent years, development of an oxide superconducting wire (a high temperature superconducting wire) such as a Y-based superconducting wire (for example, using REBa2Cu3O7−δ (a rare earth element such as RE123, RE:Y or the like)), a Bi-based superconducting wire (for example, using Bi2Sr2CaCu2O8+δ (Bi2212) or Bi2Sr2Ca2Cu3O10+δ (Bi2223)), or the like, has been performed.
In general, a Y-based superconducting wire has an intermediate layer, a superconducting layer, and a stabilized layer formed of Cu or the like, which are sequentially formed on a base material in a tape shape. The stabilized layer functions as a current pass when current is transformed from superconduction to normal conduction for any reason.
Conventionally, the Y-based superconducting wire receives tensile strength in a longitudinal direction by using a base material formed of a material having high strength, such as a Ni alloy. In addition, in the Bi-based superconducting wire, using a metal base material having high strength to increase tensile strength has been proposed.
When the superconducting wire is used as a coil, a cable, or the like, in actuality, it may be necessary to connect a plurality of superconducting wires to each other (for example, see Patent Literatures 1 to 3).
When the superconducting coil is manufactured using the superconducting wire, conventionally, a surface on which the superconducting layer is disposed is provided as an inner circumferential surface, and a connecting structure is wound in a coil shape.